Wood conduit



Dec. 14, 1943. MacKENZlE ETAL. 2,336,995

Filed 061;. 1. 1941 2 Sheets-Sheet 1 Dec. '14, 1943. N. T. MacKENZlEETAL WOOD CONDUI'I Filed Oct. 1, 1941 2 Sheets-Sheet 2 vy/anions '%J'%aPatented Dec. 14, 1943 PIECE VVQOD CONDUIT Application Qctober 1, 1941,Serial No. 413,182

(Cl. l3879) 6 Claims.

It is an object of our invention to provide a novel conduit having amultiplicity of narrow wood staves connected together by flexible metalbinding members and so arranged that the structure may be shipped incompact form and erected with a minimurn of skill and labor.

Another object is to provide a conduit of this class with a novelarrangement of binding and tensioning devices whereby the bindingmembers may be fastened and placed under high tension quickly andeasily.

Further objects are to provide low cost wood culverts and pipes of largediameter and to facilitate the handling of such conduits by furnishingthem in short, collapsible sections adapted to be erected and fittogether end to end with tight telescoping joints.

Other objects will appear and be more fully pointed out in the followingspecification and claims.

Referring to the accompanying drawings:

Figure l is a side elevation view showing a unit of our improvedconduit;

Fig. 2 is a partial and view and partial cross section of the same on alarger scale;

Fig. 3 is a side view of one our wire anchoring and tensioning devices;

Fig. l is an end View showing the unit rolled in a co ipact form forshipment and easy hanoiling;

Fig. 5 is a full size, fragmentary cross section showing one of ouranchoring and tensioning devices in operative relation to the adjoiningstaves;

Fig. 6 is an elevation of one of the staves as viewed from an edgethereof;

Fig. '7 is a detail plan view of one end of one of the binding Wires,and

Fig. 8 illustrates an alternate form of end joint, a pair of theadjoining staves being shown in side elevation.

Our improved conduit comprises a multiplicity of wood staves 8 whichshould not be less than about one and one half inches thick, threeinches wide and of a length which may be handled with ease. For conduitsof inside diameter up to 24 inches, four foot lengths are preferred. Thecost of material is reduced by utilizing standard framing lumber stockin which case the inner and outer surfaces of each stave are parallel toeach other. The side edges are shaped to converge radially inward towardthe axis of the conduit and each stave is formed along its longitudinaledges respectively with a rounded tongue or bead 9 and a similarlyshaped groove so that the edges of each stave interlock with those ofthe adjoining staves. The outer corners of each stave are beveled, asindicated at H! (Figs. 2 and 6) and the ends are rabbeted to form oneach stave an exterior tapered surface ll at one end and an interiorcomplemen tary surface l2 at the other end, permitting the units orsections of the conduit to fit together in telescoping relation end toend. The several staves are preferably impregnated with a preservativeof the toxic type, such as creosote.

Extending across the exterior surface of each stave is a plurality ofnarrow grooves E3 to receive binding wires Id. The grooves it for eachwire are aligned circumferentially of the conduit to coact with thewires in aligning the ends of the staves when the conduit is erected.One of the staves 8a of each unit is provided with a wire tensioning andanchoring device li'i for each wire it. As best shown in Figs. 3 and 5,the anchoring devices I5 comprise cap screws having heads adapted to beturned by a Wrench and cylindrical shanks it which are drilledtransversely to provide a hole 68 in each adapted to receive an end E iaof a Wire i i. A screwthreaded portion E? of each cap screw is threadedin the stave 8a in alignment with a Wire in the grooves i3 and a largecountersink 8c is formed around the screw to receive a coil of the wireend [411. The ends of the wires l i opposite the ends Ma are formed withloops Mb (Fig. '7) to em brace the shanks it of the cap screws. Forconduits up to two feet in diameter type B1312 telephone line wire maybe used as the binding Wires is, such line Wire being made of arust-resistant steel alloy having the proper degree of flexibility andadequate strength. Where the wires it cross each stave they are confinedthe grooves i3 by pairs of staples Iii.

In our alternate form of end joint, illustrated in Fig- 8, each stave 8bhas at one end a tapered surface Ila formed with a bead 25) projectingoutward and extending across said surface to fit into a similarly formedgroove in the overlying surface 52a of the adjoining stave 8b. Thestaves 3b are otherwise constructed like the staves 8, with tongues andgrooves along their side edges and grooves H817 to receive bindingwires. They may be bound together and placed under radial compression bythe wires It and devices it.

In the manufacture of our conduits, assuming that the several staves fora unit have been shaped as hereinbefore described, one of the staves 8afor each unit is formed with the countersinks 8c and fitted with anumber of the anchoring and tensioning devices I5, one in alignment witheach of the grooves [3. The wires [4 are attached by passing the shanks[5 of the cap screws respectively through the end loops Mb of the wires.The correct number of staves to form a unit are placed, edge to edge, ona flat surface with the'stave 80, along one margin of the group which ispreferably held in a suitable jig. The wires M are now placed straightacross the group from the anchoring devices and are confined in thegrooves I3 by driving pairs of the staples l9, leaving the ends Ma ofthe wires projecting from one edge of such reverse rolling produces acompact bundle which may be handled with ease by one man. Either thestave 8a or the one at the opposite margin of the mat may be placed atthe center ofthe roll. 1

When the rolled or flat units have been delivered at the sitewhere theyare to be installed, the operation of erecting the conduit may beaccomplished quickly and easily. To erect a unit starting from therolled form shown in Fig. 4, it

is merely unrolled and then bent in the reverse 5 direction so that thewires 14 encircle the exterior of the staves while the rounded tongues 9are seated in the similarly shaped grooves by rolling action. With thestaves forming substantially a cylindrical tube, the ends I la of thewires are inserted in the holes 18 of the cap screws l5 and then thesescrews are turned in by the use of a suitable wrench applied to theheads of the screws. The end portions Ma of the wires are thereby woundon the shanks 16 until the wires I4 have been placed under a suitablyhigh tension. Friction of the threads ll in the staves 8 is sufficientto retain the wires under tension. The countersinks 8c conceal andconfine the coils of wire on the shanks l6 and coact with cap screws inaffording a large range of adjustment.

With the alternate form of end joint shown in Fig. 8, after erecting onesection,-the succeeding section must be closed around the projectingbead 18 of the first completed section and "then fastened by connectingthe binding wires to the cap screw and turning the latter to produceadequate tension. Such closing of the sections around the ends of thosepreviously erected is unnecessary I with the construction illustrated inFigs. 1 to 6,

inclusive. Sections having the plane, exterior tapered surfaces II atone end and similar interior surfaces l2 at the other end may be erectedindependently of each other and then slipped into telescoping relationto each other, end to end,

to form a conduit of any desired length. Ordinarily when our conduitsare used under ground, as when used as culverts, no fastening isrequired to prevent longitudinal separation of the sections. When soused, our improved conduits have water and chemical conduits and innumerous other situations where light weight and the other peculiarcharacteristics of wood are needed.

Having described our invention, what we claim as new and desire toprotect by Letters Patent is:

1. A conduit comprising a multiplicity of wood staves shaped to fittogether edge to edge to form a pipe, flexible wires extending acrossthe exterior surfaces of said staves and a screw threaded in a stave inalignment with each of said wires, each screw having a tapered andthreaded inner end portion engaging a stave and opposite ends of eachwire being connected to one of the screws and said screws being arrangedto tension the several wires when turned inward.

2. A conduit comprising a multiplicity of wood staves having side edgesadapted to fit together edge to edge, longitudinally spaced groovesbeing formed in the exterior surfaces of said staves to receive bindingmembers, flexible binding members extending across the staves in saidgrooves, one end of each of said members being anchored on one Of saidstaves, means fastening the several staves to said members whereby thestaves are joined together as a flexible mat adapted to be rolledspirally in a compact bundle and means adapted to severally tension thebinding members upon the exterior of the staves when in tubular form.

3. A conduit comprising a multiplicity of wood staves formed withinterlocking side edges adapted to fit together edge to edge as a pipe,flexible binding wires extending across the staves, means fastening theseveral staves to said wires, whereby the staves are joined together asa flexible mat and a screw threaded in a stave in alignment with each ofsaid wires, the several screws having perforated Shanks projectingsubstantially radially from the exterior of the conduit, one end of eachof said wire being formed with a loop embracing the shank of one of saidscrews and the other end of each wire being insertable in theperforation in a shank of a screw and being adapted to be wound thereonto tension the wires on the exterior of the staves when erected as atubular shell.

4. A sectional conduit comprising, a plurality of groups of woodstaves,the staves of each group being shaped to fit together edge to edge as apipe section, flexible metal binding members extending across theexterior of the staves of each group, a tensioning device connecting theends of each binding member together to compress the staves radiallyinward, longitudinally tapered interior surfaces formed on the ends ofthe staves of one section and complementary tapered surfaces formed onthe exterior end portions of the staves of the other section to fit intelescoping relation within the first mentioned section, said tensioningdevices being operable to press the interior tapered surfaces upon saidcomplementary surfaces. I

5,. A sectional conduit comprising a plurality of groups of wood staves,the staves of each group being shaped to fit together edge to edge as apipe section, flexible binding members extending across the exterior ofthe staves of each group, means for tensioning the several bindingmembers upon the staves of each group and projecting members formed onend portions of the staves of one section to fit in interlocking,telescoping relation to complementary surfaces formed on the endportions of the staves of the other section whereby said sections may besecured end to end.

screw threaded in a, stave in alignment with each 10 of said wires, saidscrews having tapered and threaded inner end portions and being formedto engage an end of a wire and to be turned inward to wind the wirethereon for placing it under tension and the staves being formed withcountersink recesses to receive the portions of the wires which arewound on the screws.

NEAL T. MACKENZIE. HARRY E. HALL.

